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Mercedes 300D Suggestions



  • Thanks. My mechanic didn't think much of it either. So I guess that conversion is out!
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    It's very difficult to make blanket statements about these induction systems...I've seen cars on dynos with these systems installed and some do gain a few HP, some make no difference and some actually lose horsepower. You just never know until you do the dyno tests. Mostly I look at the stock system and the type of engine that's in there and try to draw some likely conclusions from that.

    Besides, a car engine is really part of a long tube...there's the mouth, the guts and the....other part out the back. If you aren't addressing the whole system, I don't think you are going to get very far.


  • You're right- engine is a part of the whole system.
    And my car is running just perfect- not having any problems; in fact I think it accelerates quite well, and I am happy with it. But diesels do like air, and compression ratio being high, I was thinking if the kit helps get more air in it, there would be less blow by maybe, more efficient use of diesel, and increased mpg. I'm sure the Germans must have thought all this many times over; so why mess with something if it ain't broke!! I'll just keep the air filter clean!
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    The system I saw in the photos looks WORSE than the stock system--it's taking hot air from the engine compartment---your stock system is at least sucking it through the grille. Besides, the general rule is 1% horsepower gain for every 10 degree drop in air temperature, so what are we talking about under the most ideal conditions? Exactly----not very much.


  • hughes2hughes2 Posts: 3
    thanks for your comments about transmission clean out! sounds like you found a mech that actually knows something about MB trannys ; a very rare person !! over here all they want to do is do a rebuild!! thanks again !!! Edmunds provide an exellent service here pitty I cant use them for biz things to make it up to them!!
  • Yes, I am very happy with my mechanic. He is fair, doesn't do things that are not necessary, and actually solves the problems. In one instance, I wanted shocks replaced because of squeaking noise from left front- he checked, said not necessary- instead replaced a linkage bar at the wheel- problem solved. I consider myself lucky; regular maintenance items I can do, and for bigger jobs take it to him!
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    I think the people who have contributed to this forum have been just outstanding. You all have a good sense of what "online community" means. I've learned a lot myself here too!

    Shifty the Host


  • Hi, I am new at this forum. maybe some of you can give me some help.
    I have a 1992 Mercedes 300D Turbo Diesel which recently started with problems on the transmission. It works fine on D position, but on Reverse it takes about 4 or 5 seconds or even more to start moving, and then the reverse shift enters very smothlly and slowlly. When the car starts moving on rear direction, it makes a strange noise like vibration or jerking, till it finally stops the noise and starts working fine. Other thing is that if I press the acelerator down to increase speed before the reverse shift is completely engaged, the car jumps a little before it starts runing right.
    I remember I had some problems before with the transmission of the same car and the problem was a vaccum valve that was in stock, do any of you have had a problem like the one I have? Remember that my problem is only in Reverse position of the shift.
    Thanks for your help.
  • Greetings, I'm new:
    Car is an '82 300 TurboD, converted to run on used veg oil (dual tank, in line heater). No previous eccentric behavior in brakes. Sat. I drove 35 mi. About midway, after accelerating from a stop I noticed a strange vibration that made the rear view mirror vibrate noticeably at 60 MPH. I assumed the worst (car about to fly apart) and was about to pull off when it diminished then went away. Upon arrival I did a walk around and found the driver rear wheel and rotor badly overheated, i.e., spit test produced sizzles.

    Next morning's return trip was uneventful, with no excessive heat on that wheel, though I drove slow and tried not to brake much. Short trip to work today normal.

    So, I'm trying to figure what, if anything, to fix before embarking on exploratory surgury. I had a similar problem once on another car that was a swollen flex brake line preventing fluid return. Also, and this is a long shot, I drove through some road oil/fresh tar last week, and it ocurred that some might have dripped onto the pads and caused the transient sticking before getting cooked off. Other ideas?

    And this followup to a recent post; I bought one of those "performance intake" packages sold on E-bay that was mentioned recently, and can point out some problems. The "K&N style" air filter is a cheap knockoff that doesn't perform well. I was notified of this by a disgruntled user and can confirm, after checking, that the filter lets fine grit into the intake, a VERY undesireable feature. Fortunately, I didn't have it installed too long. I trashed it and bought a legitimate K&N after spending quite a bit of time researching size requirements and getting one that fit the intake pipe. Also, the breather hose to the oil scavenger and intake was too small on the original and that also required a lot of retrofitting. I understand he has this fixed, but I think he is still selling the substandard filters. As for performance, seems about the same, but it does make the engine look good. and things on that side are easier to get to.

    Hints about the brake malady are appreciated.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    Your post isn't clear. You got the vibration while accelerating, or while braking at 60 mph or ????

    Spit test doesn't mean anything. Brake rotors get VERY hot in normal operation anyway. Best test is with a pyrometer, then you have a number relative to other rotors.

    Anyway, vibration while braking means a warped rotor, and it's not going to un-warp, so if that's what happened, that's one problem you have. What CAUSED the warpage is another issue.

    If you got a vibration while ACC-elerating, that's probably a wheel balance or bent wheel or driveshaft issue, but again, those things don't just go away.


  • I need to add another detail regarding the previous description. After the vibration phenomenon, I noticed that the brake pedal was spongy and non-responsive unless pumped, a sign of brake fluid vapor lock. Brake fluid level normal.

    OK, that's it.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    When's the last time you flushed out the brake fluid?


  • Thanks for the quick response. Vibration noticed after reaching highway speed, gradually worsened, then went away, but DID NOT return, either during completion of that trip or return trip, at speeds up to 60. That wheel and brake rotor were the ONLY one of four that was frying pan hot, others could be touched. Car has demonstrated no rotor vibration warpage even during stop and go city driving, when usually it is obvious.
  • It'll have nice fresh brake fluid by next week!
  • If your vibration is while braking, check your brake pads- how old are they? They could have debonded from the steel backing plate, or they could be all worn out so that there is metal to metal contact between pad/ rotor.
    And get good pads like Mintex or Pagid. I can tell you the friction material makes a hell of a lot of big difference.
    I had same problem, and my front pads were debonded.
    Tip: If you change pads, put new rotors also- they are cheap now that Chinese stuff is coming in. The aftermarket rotors have more thickness variation than OE (about 20 microns), but still ok, unless you are braking from a very high speed- then could feel some judder; but normal driving ok.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    Pagid is good, worked fine on my 300D.

    You STILL haven't told us if this vibration occurs while you are braking or while you are accelerating.


  • Vibration, and presumably overheating occurred at full speed, NOT while braking, though I had braked to a stop previously. This was followed, after some miles and disappearance of vibration, by spongy brakes. This is what made the episode so worrisome.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    Oh I see. Well then, definitely pull that wheel right away and inspect the pads, the caliper mounting bolts, rotor bolts, etc. I think this is something more than just a hydraulic issue.


  • spongy brakes = air in the system. bleed your brake lines.
    I would still check the pads. Feel the rotor- just stick your finger into the wheel (with car stopped!!!) and see if you can feel excessive grooving on the rotor-
    If caliper rubber seals are burnt, you may have a piston that's not retracting, and you may need rebuilt caliper. If stuck piston, could explain vibration even when not braking.
  • Hi, Sorry for posting my message again, but it seems that nobody saw it, maybe some of you can give me some help.
    I have a 1992 Mercedes 300D Turbo Diesel which recently started with problems on the transmission. It works fine on D position, but on Reverse it takes about 4 or 5 seconds or even more to start moving, and then the reverse shift enters very smoothly and slowlly. When the car starts moving on rear direction, it makes a strange noise like vibration or jerking, till it finally stops the noise and starts working fine. Other thing is that if I press the acelerator down to increase speed before the reverse shift is completely engaged, the car jumps a little before it starts runing right.
    I remember I had some problems before with the transmission of the same car and the problem was a vaccum valve that was in stock, do any of you have had a problem like the one I have?
    Thanks for your help.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    I'd check the fluid and if it's at the right level I'd do a major service anyway on the transmission; other than that, you'll have to tear it down and investigate I think. Noises inside a transmission are not a good sign, nor is slippage of any kind.


  • My recent transmission shifting problem was solved by cleaning the valves inside the transmission and adjusting shift points. Be sure to take it to someone who knows about MBs; ideally someone who does only MBs.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    Well anyone who works on German automatics should be okay. Grinding noise isn't a good sign though as a sticking valve body might not cause something that noticeable.


  • tijolotijolo Posts: 9
    what are some tests that I can do to check to see if my '78 300d is in need of a rebuild? Its only got 84k miles but....its burning more oil then I would expect. Constant blue smoke and burning 3.5 quarts in 2,000 miles. Half the 2,000 miles are highway miles but that seems like a lot of oil to me.
    The engine seems to be running fine, its usual sluggish self. I have changed all the filters and fluids and ran a couple of rounds of injector cleaner.
    Any suggestions would help. thanks
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,835
    cylinder leakdown test will reveal all.


  • heypeteheypete Posts: 2
    This is in reference to

    I have emailed the seller for more information, but have yet to hear back from him. Hopefully I can see the car, subject it to my extensive battery of tests (much of it gleaned from reading this thread), test-drive it, ask a ton of questions, and if everything looks good, take it to a trusted Mercedes mechanic I know to do a full inspection on it.

    According to the pictures and the (albeit brief) description, the car looks to be in good condition. Seller wants $4,300, which is a bit high. Blue Book private transfer is about $1,200. I'd probably make an initial offer around that, and haggle.

    The only potential problem I see from here is mileage: The car has 248k miles on the odometer. Status of service records is unknown, but will be asked about. I'll definitely ask to see them. I will, of course, consult with the mechanic to examine the vehicle before I'd purchase it. I'd like to get (hopefully this isn't unrealistic) at least 150k more miles out of it before having to do major work on it. I'm fairly mechanically adept, but unfamiliar with Mercedes internals...I do, however, know a few people who are rather familiar with them, and who would help me out with any hands-on work I need to do. I'd prefer to do as much work as possible myself to avoid high service costs.

    One interesting bonus: the car has been modified to run on vegetable oil, and comes with the filtering/fueling station as part of the purchase price. Depending on the quality of the station, it might be worth an extra thousand dollars, maybe more or less. The fact that the engine is pre-converted to biodiesel is a plus too, as I was hoping to do that eventually.

    Assuming I can get the car and station for $2k-$3k, and that it is cosmetically and mechanically sound, does this sound like a good deal? I realize I'm asking for an opinion on a vehicle that you have not yet inspected, and with a fairly small amount of information, and I'll take those givens into account.

  • aloha sam! this is a delayed reply to you, but thank you very much for your thorough explanation of transmission variables. i have found a 84 300d that shifts "firmly" and no slippage. (and she's gold and beautiful on a more superficial note). thank you very much for your advice,
  • aloha! i just bought a nice 84 300D with no apparent issues except.....
    after driving a couple or less minutes there occurs a whistling/squealing sound ONLY at one certain point on the pedal, the sound reappears also at this same point when decelerating. it does not matter what speed i am going, nor uphill/downhill. i haven't noticed it starting immediately upon driving, so i might venture that it doesn't happen at very low speeds.

    i reiterate: the sound is connected to very specific spot when pressing/easing the gas pedal both accelerating/decelerating. beyond that one point there are no funny sounds whatsoever and performance is fantastic

    all belts are in good shape. no leakage. no temperature issues.
    (i can't check mpg because odomoeter is broken, but it seems to be pretty damn good). i can't inspect the engine while the sound is occuring because it only occurs while driving. (unless you have some suggestions for how to?).

    my initial thought was turbocharger issues but i have limited understanding of this, so i don't understand why it would happen relevant to gas pedal and not specific speed nor gear? bearings seem unlikely since there is no sound at higher/lower speeds, increased/decreased acceleration. maybe it's not the TC and there's some linkage in the fuel system that would create such a sound? fuel pump? i just don't get it..... do any of you???

    thank you!!!!!!! (by the way, i am very happy to join all you in the ranks of MB diesel fans, this is the best car i've ever driven! it took me awhile to find her but i'm so happy i didn't settle for a subaru! biodiesel coming soon!)
  • any tips on replacing the instrument panel light and/or adjustment knob on a 84 300D, depending which one is faulty, without removing the steering wheel etc? i'm just figuring out this car, are there secret back entrances? has anyone ever just pulled out the knob and re-threaded it? i'm sketched out by little plastic breakable things.

  • 300d300d Posts: 6
    Mr shifty HELP!!!! please

    I have a 1985 300D, that and the hazards only work when they are in the mood to. I put on a new combo switch, all new fuses and a new relay. but nothing has changed. Whats next? should i go thru the harness? run a new wire? is their something in the system that i don't know about? or should i move to the front lawn and plant flower in it?
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